Junk

• A Chinese sailing vessel, see junk (sailing).
• Unwanted items in a physical sense, like junk cars. Because junk cars are a source for scrap metal spare parts, they're often sold to a junk yard, where they are typically stacked (or strewn) about a large enclosure, sometimes guarded by a "junkyard dog".
• Junk mail refers to advertising circulars, free trial CDs and other merchandising come-ons delivered by post to homes and businesses. Some people like getting this kind of stuff and respond by purchasing the goods and services offered. Many dislike or resent it, and some jurisdictions like the US have laws requiring junk mailers to withhold their offerings from residents who opt out.
• Unwanted items in a virtual sense, such as junk e-mail (see spamming).
• Junk characters in electronic text can be caused by transmission errors (line noise) and often appear as groups of "strange" letters like punctuation or accented letters. A high percentage of letters outside the standard 26-letter English alphabet often indicates the presence of junk, thus leading to filtering strategies.

See also:

• Junk food
• Junk food news
• Junk science
• Junkie